The present invention relates generally to improvements in automotive dual fuel tank systems and more particularly to improvements in automotive fuel tank systems with multiple fuel tanks and a single fuel fill nozzle.
Automotive fuel tank systems are well known in the automotive industry. The design of fuel tank systems is often a balance of the cost, weight, complexity, and safety of such designs with the convenience and satisfaction they provide to the customer. One such area of customer convenience and satisfaction is in the area of fuel tank volume.
Increasing the fuel tank volume can lead to increased consumer convenience and satisfaction by providing a greater vehicle range and longer periods of time before requiring a fill-up. This can be additionally important to consumers in automobiles such as sport utility vehicles, where a faster consumption of fuel can shorten vehicle range and time between fill-ups. However, the convenience and satisfaction provided by larger fuel tank volume must be balanced with vehicle weight, safety, cost, and impact on other systems within the automobile.
It is known that the fuel tank volume can be increased through the use of dual fuel tanks. Dual fuel tanks can be used to increase fuel volume while reducing the impact on other automotive systems when compared to a single large tank. It is known, however, that some existing designs for dual fuel tanks can have disadvantages.
One known disadvantage is that dual fuel tanks can require separate fill hoses for each fuel tank. This is highly undesirable since the need to fill separate tanks can lead to customer dissatisfaction. It is known that the use of a single fill hose is more desirable since it improves customer convenience.
Another disadvantage is that fuel can be supplied to the automobile from either or both tanks. One known method utilizes a change-over valve, such that when fuel in one tank is diminished, the valve can switch the source to the other tank. This design can lead to high production and warranty costs, as well as lowered customer dissatisfaction due to malfunctioning valves. A cheaper and more simplistic design for distributing fuel would be highly desirable.
A known method uses a tube to equalize the levels in each tank. Although this method reduces the cost and complexity of design, it has disadvantages as well. This system relies on gravity to supply fuel to the lowest point in the fuel tanks where the fuel is pumped out. This system, however, can function improperly when the vehicle is on an incline that prevents fuel flow to the lowest portion of the fuel system. In addition, the tube that provides a connection between the two fuel tanks must be located near the bottom of each fuel tank for the fuel to be properly distributed. This can create dangerous structural and safety problems. This design places the tube close to the bottom of the vehicle where it may be exposed to damage from collision or foreign objects. A fuel fill system that retains the simplicity of known gravity tube distribution systems, but that worked at a greater range of vehicle angles and reduced the chance of structural damage to the fuel transfer system, would be highly desirable.
Although dual fuel tanks can increase the volume of fuel available to the automobile, they also can increase the weight of the vehicle which is undesirable. It is known that fuel tanks can be created out of plastic to provide a cheaper and lighter alternative to steel tanks. In addition, it is known that the use of low permeability material can reduce fuel hydrocarbon emissions and thereby meet government emission standards. Although fuel tanks made out of plastic materials can be cheaper, lighter and reduce emissions, they also have size limitations. Fuel tanks positioned forward of the rear axle of a vehicle are limited in capacity by the available packaging space. Plastic fuel tanks positioned aft of the rear axle of a vehicle must be protected from hot exhaust gases, exhaust pipe rupture, foreign objects, collision, broken shocks, and other damaging events. Protecting plastic fuel tanks positioned aft of the rear axle from these events can be costly. The smaller the plastic fuel tank behind the rear axle, however, the easier and less expensive it is to protect it from these events. It would be highly desirable to have a fuel tank design that would utilize the cost and weight savings of plastic fuel tanks while reducing the safety costs and concerns limiting present plastic fuel systems.
It is therefore an object of the present invention to provide a dual fuel tank that maximizes fuel volume while providing adequate fuel supply at a greater range of vehicle angles. It is a further object of the present invention to provide a dual fuel tank that reduces the costs associated with known designs and increases customer convenience.
In accordance with the object of this invention a dual fuel tank system is provided. The dual fuel tank system includes a first fuel tank and a second fuel tank. The dual fuel tank also includes a transfer tube that is in fluid connection with both fuel tanks. The transfer tube allows overflow from the first fuel tank to enter the second fuel tank such that both tanks can be filled from a single fill hose in fluid connection with the first fuel tank.
A transfer fuel pump moves fuel from the second fuel tank into the first fuel tank. In this manner, the volume of fuel in the first fuel tank is kept at a maximum level. By keeping the volume of fuel in the first fuel tank at a maximum and only allowing overflow fuel to transfer from the first fuel tank into the second fuel tank, an adequate supply of fuel is available in the fist fuel tank at a wider range of vehicle angles. A main fuel pump communicates fuel from the first fuel pump to a remote target within the automobile.
Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.